Lots of us use four-digit PINs to protect our debit cards and phones, but anybody with basic math skills can tell that four characters — made up of numbers zero through nine — aren't exceptionally secure. Even worse, users make the situation riskier by mostly using the same handful of PINs for various services.

Redditor u/infobeautiful posted a chart analyzing every possible four-digit PIN and how often they're used, according to 3,400,000 real PINs found through data breaches.

Unfortunately, it's obvious that people aren't taking their security seriously.

Key findings:

• Down in the bottom-left of the chart, you'll see a lot of highly used numbers that indicate people are using their birthday as the PIN.

• Similarly, there's a strip of numbers starting with 19 and 20 indicating that folks are using their birth year as a four-digit PIN.

• The diagonal strip shows that people are using pairs of numbers to make punching in their code faster.

• 1234 and 4321 are overused too, so don't try it, pal.

• According to the title of the Reddit post, the top 20 combinations make up over a quarter of real world PINs — making them exceedingly easy to guess.

• Changing your PIN to something even a little less common will make it harder for ne'er-do-wells to crack. Or, even better, switch over to a more complex password where possible (like your smartphone lock screen).

Click image to enlarge

Via u/infobeautiful.